Quick Facts

Quick facts

• Texas Blueweed (Helianthus ciliaris) is native to the United States of America.
• In Australia, Texas Blueweed is naturalised only in New South Wales.
• In the United States of America, it is highly competitive in several crops and cropping systems, including cotton, wheat, and sorghum.
• In its native habitat, it grows in low densities in native grasslands, but it thrives in cultivated or heavily disturbed areas.
• It is spread by root fragments and herbicide use offers the most effective means of control.

What Does It Look Like?

What is it?

Texas Blueweed (Helianthus ciliaris) is a perennial herb with slender, creeping, rhizome-like roots, but without true rhizomes or thickened storage organs. It is 40–70 cm high and often forms extensive colonies. The stems are blue-green and partially trailing or fully upright, and either hairless or with scattered stout hairs. The stalkless leaves are arranged along the length of the stem, mostly opposite, and are blue-green. They are narrow to lance-shaped, 30–75 mm long and 5–22 mm wide, with smooth or toothed margins, flat or often with folded back or ruffled margins, hairless except for minute hairs along the margins, and are one- or three-nerved.

The flowering heads are single or in groups of three or four, terminating the branches, on stalks 30–150 mm long. The heads are 15–25 mm in diameter. There are 10–18 yellow petal-like segments (ray florets) around the outside, with blades 8–10 mm long. The inner, tubular florets (disc florets) are reddish-purplish and yellow.

The fruits are 3–3.5 mm long, black or greyish at maturity, with two bristled scales, 1.2–1.5 mm long (Murray 1992; Cronquist 1994; Schilling 2006).

For further information and assistance with identification of Texas Blueweed, contact the herbarium in your state or territory.

Flower colour

Yellow, Purple

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Texas Blueweed is native to the grasslands of the south central United States of America. It grows naturally in low densities in native grasslands, but thrives in cultivated or heavily disturbed areas. It also inhabits roadsides, streams and ditch banks, and open drainage areas, often preferring alkaline and saline soils. It occurs from 10–2600 m above sea level (Kearney et al. 1964; Martin & Hutchins 1981; Cronquist 1994; Schilling 2006; California Department of Food and Agriculture undated).

Habitat notes from specimens held at the National Herbarium of New South Wales record the species growing in a cultivated paddock, a moist gully on roadside in coarse, light-textured soil and in grey loam wheat soils (National Herbarium of New South Wales 2008).

Are there similar species?

Two other species of Helianthus are naturalised in Australia: Common Sunflower (Helianthus annuus) and Jerusalem Artichoke (Helianthus tuberosus). Common Sunflower is an erect annual or biennial herb, 1–2 m high, with a taproot, and egg-shaped or heart-shaped leaves. Jerusalem Artichoke is a perennial herb with short rhizomes and tubers, and grows to 1.5–3 m high. Texas Blueweed differs from both the Common Sunflower and the Jerusalem Artichoke in having hairless leaves. The leaves of Common Sunflower are rough, with firm, stiff hairs, and those of Jerusalem Artichoke are rough to touch being covered with minute, stiff hairs on the upper surface, and softly hairy on the lower surface. Texas Blueweed also has smaller flower heads, 8–10 mm across, compared with 2–8 cm or wider in the Common Sunflower and the Jerusalem Artichoke, which also have longer petal-like segments (20–40 mm, compared with 8–10 mm in Texas Blueweed (Murray 1992).

Why Is It A Weed?

What are its impacts?

Agriculture: In the United States of America, Texas Blueweed is highly competitive in several crops and cropping systems, including cotton, wheat, and sorghum (California Department of Food and Agriculture undated). There is virtually no published information about the impact of Texas Blueweed on the environment or agriculture in Australia. At Milford, in Queensland, it was recorded as densely infesting 4 acres in a paddock in 1951, but there are no subsequent records from this area (Queensland Herbarium 2008).

How does it spread?

Vegetative spread by root fragments is the chief means of reproduction of Texas Blueweed. Root fragments are commonly spread by machinery dragging fragments from infested areas to clean sites. It also reproduces by seed, but seed viability is often very low, sometimes less than 1% (California Department of Food and Agriculture undated).

What is its history in Australia?

The earliest herbarium specimen of Texas Blueweed in Australia, collected in 1935, is from the Forbes area of the Central West Slopes region of New South Wales (National Herbarium of New South Wales 2008). It is not known how it was introduced to Australia.

How To Manage It?

Best practice management

Non-chemical control: Physical control: In the United States of America, isolated plants of Texas Blueweed and small infestations are physically hand pulled, hoed or grubbed, and the site is monitored over several years to ensure that any resprouting plants are destroyed. In pasture situations, Texas Blueweed can be prevented from establishing by maintaining a vigorous, competitive pasture. Texas Blueweed is grazed when young, but tends to be avoided by stock as it matures. Overgrazing of the pasture by stock encourages the growth of Texas Blueweed (California Department of Food and Agriculture undated) and should therefore be avoided.

Mechanical control: Because Texas Blueweed is spread by root fragments, mechanical disturbance of infestations will only exacerbate the problem. The movement of agricultural seeds, grain, forage, fodder, soil and machinery contaminated with seeds, and particularly root fragments, from infested areas to clean areas needs to be restricted (Stajsic pers.comm. 2008).

Chemical control: Herbicides probably provide the most effective means of controlling Texas Blueweed. In the United States of America, several herbicides have been reported as effective in controlling the species. These herbicides need to be applied during the growing season of the plant (California Department of Food and Agriculture undated).

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

In Australia, Texas Blueweed flowers primarily in late spring and summer (Murray 1992; Queensland Herbarium 2008).

Where Is It Found?

Which states and territories is it found?

NSW, QLD

What areas within states and territories is it found?

Texas Blueweed has been recorded once in Queensland, at Milford near Boonah, in 1951 (BRI 2008). It is believed to have been introduced at the site about ten years before collection of the herbarium specimen from that area. The notes indicate that ploughing and cultivating appeared to increase the spread of Texas Blueweed at the site. At the time of collection in 1951, the extent of the incursion was over 4 acres in a paddock (Queensland Herbarium 2008). There have not been any subsequent records of the species in Queensland, and the species is not considered naturalised in that state on the basis it hasn't been collected for at least 50 years (Bostock & Holland 2007).

Texas Blueweed is only considered to be naturalised in New South Wales, where it is widespread from north of the Victorian border in the South West Slopes region to Coonabarabran in the North West Slopes region (AVH 2008; National Herbarium of New South Wales 2008).

Where does it originate?

Texas Blueweed is native to the United States of America (Kansas, Oklahoma, New Mexico, Texas, Arizona) and Mexico, and it has naturalised elsewhere in North America (GRIN 2008).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NSW, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Helianthus ciliaris

Other scientific names (synonyms)?

Does it have other known common name(s)?

Blueweed, Blueweed Sunflower, Yerba Parda